Pesticide Residues and Exposure - ACS Publications - American

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7 Pesticide Safety Program of the California Department of Food and Agriculture Based upon Measurements of Potential Workplace Exposure and the Elimination of Excess Exposures Κ. T. MADDY and S. C. EDMISTON California Department of Food and Agriculture, Worker Health and Safety Unit, Sacramento, CA 95814

P e s t i c i d e s are selected because they have s p e c i f i c b i o l o g i c a l e f f e c t s ; u s u a l l y they are t o x i c t o some organism. These chemicals may not have an acute t o x i c e f f e c t on man, but o f t e n , with adequate dosage through time, adverse e f f e c t s may occur. The p e s t i c i d e safety program of the C a l i f o r n i a Department of Food and A g r i c u l t u r e has included the taking of measurements o f : (1) p e s t i c i d e vapors and mists i n the breathing zone o f persons exposed; (2) p e s t i c i d e residues on the s k i n and c l o t h i n g o f persons applying p e s t i c i d e s ; and (3) p e s t i c i d e r e s i d u e s , i n c l u d ing more t o x i c breakdown products on f o l i a g e and s o i l i n f i e l d s where work i s t o take place subsequent t o a p p l i c a t i o n . In the past, l i t t l e of t h i s type of information was supplied by p e s t i cide r e g i s t r a n t s . Studies to monitor exposure l e v e l s of p e s t i cides i n the workplace are being conducted by the Department f o r c e r t a i n p e s t i c i d e s already r e g i s t e r e d ; a l s o , these kinds of data are now being requested from the r e g i s t r a n t s p r i o r t o r e g i s t r a t i o n of c e r t a i n products. These measurements are of value i n designing ways to keep exposures o f users a t low l e v e l s . Discuss ion I t i s considered d e s i r a b l e t o keep workplace exposure t o p e s t i c i d e s as low as p r a c t i c a l regardless of the current know ledge o f t h e i r a c u t e and c h r o n i c t o x i c i t y . A l l too often p e s t i c i d e s which were considered t o be of n e g l i g i b l e t o x i c i t y are l a t e r found t o have a p o t e n t i a l f o r causing adverse h e a l t h e f f e c t s f o l l o w i n g a s u f f i c i e n t period of exposure t o an adequate dose. DBCP and nitrophen are good examples o f t h i s type of problem. We a l s o gather and analyze d e t a i l e d information on more than 2,000 i l l n e s s reports per year from physicians who d e s c r i b e p o s s i b l e occupational exposures t o s p e c i f i c p e s t i c i d e s . We a l s o obtain or make d e t a i l e d workplace measurements o f the l e v e l s of p e s t i c i d e s t o which workers may be exposed. 0097-6156/82/0182-0075$05.00/0 © 1982 American Chemical Society

Plimmer; Pesticide Residues and Exposure ACS Symposium Series; American Chemical Society: Washington, DC, 1982.


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PESTICIDE RESIDUES AND EXPOSURE

I n h a l a t i o n Exposure L e v e l s . For s e t t i n g acceptable maximum i n h a l a t i o n exposure l e v e l s , we u s u a l l y use the lowest t h r e s h o l d l i m i t values of those set by Federal OSHA (Occupational Safety and H e a l t h A d m i n i s t r a t i o n ) , C a l i f o r n i a OSHA, or the ACGIH (American Conference of Governmental I n d u s t r i a l H y g i e n i s t s ) . Sometimes, as with ethylene dibromide, we accept a NIOSH (Nat i o n a l I n s t i t u t e of Occupational Safety and Health) recommended standard which i s lower than the three s t a n d a r d - s e t t i n g e n t i t i e s p r e v i o u s l y mentioned. In other cases, when a standard has not been set by any of these groups, we set one ourselves based on a v a i l a b l e i n h a l a t i o n t o x i c i t y information. Dermal Exposure L e v e l s . S e t t i n g acceptable maximum dermal exposure l e v e l s t o s p e c i f i c p e s t i c i d e s has been d i f f i c u l t . This i s p r i m a r i l y due to a l a c k of s p e c i f i c data on dermal t r a n s p o r t r a t e s f o r s p e c i f i c p e s t i c i d e s as r e l a t e d t o a d v e r s e e f f e c t l e v e l s and presumed n o - e f f e c t l e v e l s . We are now r e q u i r i n g such data from the r e g i s t r a n t s , and our Department has a suggested p r o t o c o l 0_) that i s o f f e r e d to r e g i s t r a n t s that w i l l provide such information from animal exposure s t u d i e s . This dermal t r a n s p o r t r a t e information i s important i n s e t t i n g minimum f i e l d r e e n t r y i n t e r v a l s f o r f i e l d workers as w e l l as i n e v a l u a t i n g exposure l e v e l s of mixers, l o a d e r s , and a p p l i c a t o r s . I f the products are c h o l i n e s t e r a s e i n h i b i t o r s , a dermal dose-response r a t e p r o t o c o l (2) i s recommended.

Reentry-Type Data. Reentry-type data p e r t a i n i n g to e n t e r ing areas where p l a n t s have been t r e a t e d w i t h p e s t i c i d e s i s needed i n c e r t a i n s i t u a t i o n s t o determine i f a p o t e n t i a l hazard e x i s t s f o r w o r k e r s who might go back i n t o a t r e a t e d a r e a . The f o l l o w i n g i s a g u i d e l i n e suggested and used by the Department i n d e c i d i n g whether or not r e e n t r y data i s needed: The product i s to be a p p l i e d to a plant and, p a r t i c u l a r l y , to i t s f o l i a g e , and C u l t u r a l p r a c t i c e s (such as pruning or h a r v e s t i n g ) of that crop involve s u b s t a n t i a l (human) body contact with f o l i a g e or bark or exposure to p e s t i c i d e residues shaken from the f o l i a g e or bark, and The product c o n t a i n s : a. ) a c h o l i n e s t e r a s e i n h i b i t o r , or. b. ) a s i g n i f i c a n t l y t o x i c p r i n c i p l e that can cause a d e t r i m e n t a l a c u t e s y s t e m i c t o x i c r e a c t i o n or i s s u s p e c t e d o f c a u s i n g a c h r o n i c e f f e c t , and may be r e a d i l y absorbed through the s k i n or_ inhaled f o l l o w i n g exposure to p e s t i c i d e residues contacted while conducting usual c u l t u r a l p r a c t i c e s , or_ c. ) a chemical which causes a s i g n i f i c a n t primary s k i n i r r i t a n t r e a c t i o n i n appropriate t e s t animals or man, or


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d.) a chemical which i s a s i g n i f i c a n t s k i n s e n s i t i z e r i n appropriate t e s t animals or man. There a r e s e v e r a l s u g g e s t e d s o u r c e s which a r e u s e f u l g u i d e l i n e s f o r determining residues of p e s t i c i d e s on s o i l and l e a f s u r f a c e s ( d i s l o d g e a b l e ) and c o n d u c t i n g f i e l d r e e n t r y studies i n v o l v i n g human volunteers ( 3 ) , ( 4 ) , and (5.). Human exposure s t u d i e s may not be required i f adequate animal dermal d o s e - r e s p o n s e d a t a , as w e l l as o t h e r d a t a , a r e a v a i l a b l e . M i x e r , L o a d e r , A p p l i c a t o r Exposure S t u d i e s . A major d i f f i c u l t y i n making hazard assessments f o r mixers, l o a d e r s , and a p p l i c a t o r s i s t h e l a c k o f i n f o r m a t i o n on how much o f t h e p e s t i c i d e may be inhaled or may reach the s k i n under a t y p i c a l use s i t u a t i o n . The f o l l o w i n g i s an example o f a p r o t o c o l used by t h e Department i n conducting our studies on p r e v i o u s l y r e g i s t e r e d p e s t i c i d e s t o measure exposure l e v e l s of mixers, loaders and applicators. This i s the g u i d e l i n e that i s suggested by the Department and i s provided t o r e g i s t r a n t s . From data c o l l e c t e d i n t h i s manner, along with the dermal absorption or dermal dose response data, we can determine the adequacy of l a b e l i n s t r u c t i o n s i n minimizing exposure l e v e l s . Substance t o be t e s t e d : Testing should be performed using the formulated product t o be marketed and i n accordance w i t h the proposed l a b e l . Rate of a p p l i c a t i o n : At l e a s t some of the a p p l i c a t i o n s being studied should be at the maximum use r a t e s p e c i f i e d on the label. Exposure: The period of exposure studied should be at l e a s t one work day and o f t e n f o r longer periods. Sufficient work should be accomplished during the work day to a l l o w i n v e s t i g a t o r s to c o l l e c t meaningful and r e p r e s e n t a t i v e data. Number o f workers: S u f f i c i e n t numbers o f workers should be monitored during the study. Reported values should include data from at l e a s t four workers. Informed consent and appropriate human subjects review are required f o r s t u d i e s done i n C a l i f o r n i a i f the p e s t i c i d e or the use being studied does not have f u l l California registration. Workers: The workers should be employees who are r o u t i n e l y engaged i n the mixing-loading or a p p l i c a t i o n of p e s t i c i d e s . Protective clothing: Protective clothing (usually including long-sleeved cotton c o v e r a l l s ) and p r o t e c t i v e equipment, such as approved r e s p i r a t o r s , rubber gloves, and rubber foot covering must be worn t o prevent or reduce exposure i f proposed for or already on the e x i s i t i n g l a b e l i n g . T o x i c i t y category one l i q u i d p e s t i c i d e s should be t r a n s f e r r e d from t h e i r o r i g i n a l containers t o mixing or a p p l i c a t i o n tanks through closed t r a n s f e r systems. Measuring c l o t h i n g or dermal exposure: A c l o t h pad sampl i n g technique may be used t o determine the amount of p e s t i c i d e



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sprayed or s p i l l e d on c l o t h i n g and s k i n . Hand exposure can be measured by hand-washing procedures. Other techniques such as those i n v o l v i n g s k i n wiping procedures or those i n v o l v i n g the use of f l u o r e s c e n t b r i g h t e n e r s may be used t o e s t i m a t e the amount of p e s t i c i d e deposited on c l o t h i n g or s k i n . C o l l e c t i n g a i r samples: An a p p r o p r i a t e number of a i r samples should be taken during the work day to e s t a b l i s h the amount of p e s t i c i d e i n the breathing zone of the worker during normal work o p e r a t i o n . This would u s u a l l y involve the worker's wearing b a t t e r y powered a i r pumps p u l l i n g a i r through approp r i a t e s a m p l i n g media. Measurements s h o u l d be t a k e n from both i n s i d e and outside the worker's r e s p i r a t o r . Measuring dermal absorption: U r i n e , blood, and/or f e c a l samples s h o u l d be c o l l e c t e d at the end of each work day t o determine the presence or absence of the parent chemical or metabolites. Samples may be c o l l e c t e d at other times depending upon how the c h e m i c a l i s m e t a b o l i z e d i n the body. I f the product i s a c h o l i n e s t e r a s e (ChE) i n h i b i t o r , blood c h o l i n e s t e r a s e measurements should be made p r i o r t o and a f t e r exposure. I t may be appropriate to examine the blood and u r i n e f o r changes from the normal c h a r a c t e r i s t i c s , or to make other medical t e s t s approp r i a t e to the p e s t i c i d e ' s p a r t i c u l a r e f f e c t s . Suggested methods: The study should be s t a r t e d at the beginning of a r e p r e s e n t a t i v e work day. Attach c l o t h patches to the s k i n areas of the back and f r o n t of the neck, on each cheek, and to c l o t h i n g (two per s i t e ) at the shoulder, lower s l e e v e , chest, w a i s t , and knees. Wash the worker's hands w i t h 200 mL of soapy water and/or e t h y l a l c o h o l at the end of the work p e r i o d . C o l l e c t a i r samples i n the breathing zone of the worker during the e n t i r e work day, u s u a l l y i n s i d e and outside a r e s p i r a t o r . C o l l e c t blood, u r i n e , and/or f e c a l samples at the end of the work day and/or other times when a p p r o p r i a t e . Analyze c l o t h patches and a i r samples f o r p e s t i c i d e s . Analyze u r i n e samples f o r parent compound and i t s m e t a b o l i t e s , and blood samples f o r ChE a c t i v i t y or other expected chemicals or changes i n body chemistry. Repeat the process s e v e r a l times to o b t a i n s u f f i c i e n t information f o r e v a l u a t i o n . Evaluation: The work s i t u a t i o n being studied should be c a r e f u l l y s e l e c t e d and described so that i t can be determined i f i t i s t y p i c a l of current p r a c t i c e s , of those on the l a b e l , or i f d i f f e r e n t work p r a c t i c e s were i n e f f e c t . At the completion of the study, the data obtained should be evaluated i n r e l a t i o n s h i p to exposure (dermal and i n h a l a t i o n ) , a b s o r p t i o n ( u r i n a r y m e t a b o l i t e s ) , e f f e c t s (ChE i n h i b i t e d ) , acute, c h r o n i c , and metabolic studies i n l a b o r a t o r y animals. These f i n d i n g s should then be evaluated and discussed i n r e l a t i o n to e x i s t i n g or proposed l a b e l i n g or r e g u l a t i o n s . P r o t o c o l s : A study by Durham and Wolfe (6) provides u s e f u l p r o t o c o l guidance f o r mixer, loader, and a p p l i c a t o r s t u d i e s .



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The Department considers the p r o t o c o l s used i n the Durham and Wolfe (6) study as q u i t e u s e f u l guides; however, the percentage of the body reported as exposed i n that study i s considered as underreported unless impervious c l o t h i n g i s worn. The Department u s u a l l y considers the s k i n on the e n t i r e body t o be s u b j e c t t o some e x p o s u r e . We use d a t a from two a r t i c l e s as r e f e r e n c e s f o r d e t e r m i n i n g t o t a l body s u r f a c e a r e a ; one by Berkow and Amboy (_7) , and a n o t h e r by DuBois and Dubois (8) . Use of Data Obtained: When data i s r e c e i v e d , such as that provided by a study conducted as suggested above, an assessment is made as to the adequacy of l a b e l i n s t r u c t i o n s i n m i t i g a t i n g any perceived hazards of use. The l a b e l may be accepted and the product may be r e g i s t e r e d without f u r t h e r concern. On the other hand, one or more of the f o l l o w i n g c o n d i t i o n s may be r e q u i r e d : (1) The E n v i r o n m e n t a l P r o t e c t i o n Agency (EPA) may be advised of the d e s i r a b i l i t y of r e q u i r i n g a l a b e l change, (2) a use r e g u l a t i o n may be enacted which w i l l have the same e f f e c t as a l a b e l change, (3) the use of the product may be r e s t r i c t e d , (4) closed system t r a n s f e r of l i q u i d p e s t i c i d e s may be r e q u i r e d , (5) changes i n t h e p r o d u c t may be r e q u i r e d t o reduce e x c e s s dustiness (and thus the h a z a r d ) , (6) w a t e r - s o l u b l e packaging of t h e more t o x i c powders may be r e q u i r e d , ( 7 ) minimum f i e l d r e e n t r y i n t e r v a l s may be set by r e g u l a t i o n , (8) medical superv i s i o n may be r e q u i r e d , and/or (9) d e t a i l e d s a f e t y t r a i n i n g may be required f o r s p e c i f i c p e s t i c i d e s . The use of closed systems has been required i n C a l i f o r n i a for t r a n s f e r of t o x i c i t y category one l i q u i d p e s t i c i d e s from the manufacturer's c o n t a i n e r i n t o the mix tank and then into the a p p l i c a t i o n v e h i c l e tank. I t appears t h a t t h i s p r o c e s s has considerably reduced both dermal and i n h a l a t i o n exposure. The use of probes that are i n s e r t e d and then removed from containers reduces dermal exposure up t o t e n - f o l d ; i t a l s o appears that the use of b u i l t - i n probes f u r t h e r reduces exposure to the mixerloader by up to another t e n - f o l d f a c t o r i n some cases. Conclus ions No one enjoys complying w i t h d e t a i l e d government r e g u l a t o r y requirements or l a b e l i n s t r u c t i o n s . E f f o r t s are made t o avoid r e g u l a t o r y o v e r k i l l to the point that i t would appear that most p e s t i c i d e s i n use are h i g h l y hazardous. Excessive warnings on every use of every product could lead t o workers t a k i n g a casual a t t i t u d e i n t h e i r use of a l l products. On the other hand, there has been so much s c r u t i n y and concern about the use of p e s t i cides i n recent years that i t i s important t o base safe use of p e s t i c i d e s on the best p o s s i b l e t e c h n i c a l information. This i s of b e n e f i t to (1) the manufacturer who has spent m i l l i o n s of d o l l a r s i n developing a product and wishes to continue to s e l l i t , ( 2 ) t h e u s e r s who may c o l l e c t i v e l y r e c e i v e b e n e f i t s i n



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the m i l l i o n s of d o l l a r s from the proper use of the product, as w e l l as (3) the many members o f the general p u b l i c who have concerns that p e s t i c i d e s are not being used as c a r e f u l l y as considered d e s i r a b l e .


Abstract Pesticides are selected because they have specific bio logical effects; usually they are toxic to some organism. These chemicals may not have an acute toxic effect on man, but often, with adequate dosage through time, adverse effects may occur. The pesticide safety program of the California Department of Food and Agriculture has included the taking of measurements of: (1) pesticide vapors and mists in the breathing zone of persons exposed; (2) pesticide residues on the skin and clothing of persons applying pesticides; and (3) pesticide residues, including more toxic breakdown-products on foliage and soil in fields where work is to take place subsequent to application. Once these measurements are made and their significance is assessed: (1) medical supervision may be required; (2) safe-use wording on the label may be recommended through the Environ mental Protection Agency; (3) protective clothing and use procedures may be changed by regulation; (4) safety information leaflets may be issued to supplement safety training and to condition use permits; (5) closed-system transfer of liquid pesticides may be required; (6) water-soluble packaging or reduction of dustiness of the more toxic wettable powders may be recommended; and (7) field reentry times may be set by regula tion to minimize human exposure to pesticides. Most aspects of the safety program have focused on separating man from the pesticide and its residues.

Literature Cited 1.

California Department of Food and Agriculture, Operational Protocol For Pesticide Registration and Evaluation, 1979, page B5, 1220 Ν Street, Sacramento, California 95814.

2.

Knaak. J. B., P. Schlocker, C. R. Ackerman and J. N. Seiber Reentry research: establishment of safe pesticide levels on foliage. Bull. Environ. Contam. and Toxicol., 1980, 24, 796.

3.

Iwata, Y., J . B. Knaak, R. C. Spear, and R. J . Foster Worker Reentry Into Pesticide-Treated Crops, I., Procedure for the determination of dislodgeable pesticide residues on foliage, Bull. Environ. Contam. Toxicol., 1977, 18, 649.



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4.

Spencer, W. F . , Y. Iwata, W. Ν. Kilgore and J . B. Knaak Worker reentry into pesticide-treated crops, I I . , proce dures for the determination of pesticide residues on the soil surface, Bull. Environ. Contam. Toxicol., 1977, 18, 656.

5.

Kahn, E. Outline guide for performance of field studies to establish safe reentry intervals for organophosphate pesti cides, Residue Reviews, 1979, 70, 27.

6.

Durham, W. F. and Wolfe, H. R.: Measurement of Exposure of Workers to Pesticides, Bull. of World Health Organization, 1962, 26, 75.

7.

Berkow, S. G. and Amboy, P., Value of surface area pro portions in the prognosis of cutaneous burns and scalds, Amer. Jour. of Surgery, 1931, 11, 315.

8.

DuBois, D. and DuBois, E. F . , Clinical Calorimetry, 10th paper. A formula to estimate the approximate surface area i f height and weight be known, Arch. of Internal Medicine, 1916, 17, 863.

RECEIVED May 19, 1981.


Pesticide Residues and Exposure - ACS Publications - American

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